The invention relates to a medical device known as a foot pump for therapeutic application of transient squeezing action on the pool of blood which accumulates in the plantar region of a foot and which is normally returned for recycled use, via the venous system serving the human leg. The invention represents an improvement with respect to devices disclosed in U.S. Pat. No. Re. 32,939, and the disclosures of said reissue patent are incorporated herein by reference.
The devices of said reissue patent had their origin in the inventors' discovery that in a normal ambulatory human being, the very fact of walking, wherein body weight is alternated in application first to one leg and then to the other, has the normal effect, in response to weight-bearing, of transiently forcing apart the ball and heel of the foot, followed by a relaxation process in which the load of body weight is transferred to the other foot. As a result, the vessels in which blood accumulates in the plantar region between the ball and heel are transiently stretched to reduce blood-vessel section area, and blood is expelled for return to the heart via the venous system. For bed-ridden patients and those having a limited range of ambulation, the normal processes of venous return necessarily suffer, and the impulse-driven inflatable foot pump is proving ever more helpful, even if primarily only to reduce pain in a leg injury.
The said reissue patent discloses a fitted slipper, for use with an applied inflatable bag, and the patent also suggests incorporating an inflatable bag in a boot, to enable a patient's limited ambulation, while temporarily disconnected from the source of pulsed inflation air required for foot-pump operation. But the fitted slipper and the suggested boot are devoid of any suggestion of how to provide maximum comfort, convenience of application and removal, all at such low cost as to classify the item as disposable, i.e., not reusable by another patient.